The Heart’s Own Immune Cells Can Help It Heal

November 10, 2014

Researchers at Washington University have found the heart holds its own pool of immune cells capable of helping it heal after injury, according to a new study in mice at Washington University School of Medicine in St Louis. Research led by cardiologist Dr. Kory Levine, showed that the injured pediatric and adult heart contains two types of macrophages with different developmental origins, a finding that may explain why the failing pediatric heart has a greater capacity for cardiac recover.

“Researchers have known for some time that the neonatal mouse heart can completely recover from injury, and in some cases can even regenerate,” said the first author Kory J. Lavine, MD, PhD, instructor in medicine. “If you cut off the tip of the neonatal heart, it forms scar tissue.” Dr. Lavine hypothesized that differences in the innate immune system might explain the disparity in healing capacity between the neonatal and adult heart.

Macrophages are a central component of the innate immune system and are required for clearance of pathogens, inflammatory responses, and wound healing. How these immune cells perform such diverse functions is not well understood. Using a mouse model of cardiac injury to simulate heart failure, the injured pediatric heart contained macrophages of embryonic origin that stimulated tissue repair, while the injured adult heart contained macrophages recruited from the bone marrow that generated inflammation and imparted additional damage to the heart. “The same macrophages that promote healing after injury in the neonatal heart also are present in the adult heart, however they disappear following injury.” The research team additionally found that by blocking recruitment of macrophages from the bone marrow to the injured adult heart, they were able to preserve the pool of beneficial embryonic macrophages and improve the reparative capacity of the adult heart. Their findings implicate a new potential therapeutic approach for treating patients with heart failure. This article appeared online November 10th, on the National Institutes of Health site.